Urethane foam which is orthogonally reinforced with filaments is an effective cryogenic insulation. One use of such insulation is in insulating compartments or holds of marine vessels used to transport liquid natural gas. Transporting natural gas in its liquid state (at cryogenic temperatures) is preferable to transporting it in its gaseous state since it is reduced in volume approximately 600 times. In one form, a metal storage tank is spaced from the hull of the vessel and insulation is applied to the inside of the tank.
The reinforcement for such foam insulation is preferably in the form of adjacent layers of X-Y fibers through which Z or vertical filaments are inserted to form an X-Y-Z orthogonal array. Urethane or equivalent foam is passed through the filamentary array and after sufficient cure, the foamed array is cut into desired length, forming planks of foam insulation which can then be bonded together to form the above noted cryogenic insulation.
The present invention is directed to the fabrication of an open weave scrim cloth formed of one or more layers of uniformly spaced fibers or filaments in the X (longitudinal) direction and Y (transverse) direction, and is particularly concerned with a novel method and apparatus for stringing the Y filaments in a transverse direction between oppositely facing hooks mounted on opposite moveable longitudinal side panels, to form a plurality of longitudinally spaced Y filaments, with means being provided for paying off the X filaments in a longitudinal direction between the Y weaving filament stations.
The presently known scrim cloth weaving mechanisms generally utilize shuttles and have pay-off mechanisms which do not allow the cloth to be mounted one layer above the other, and spaced a discrete distance apart, on hooks or tenter pins mounted on side panels, during fabrication of the cloth.
Representative of the prior art disclosing X and Y filament weaving mechanisms are the following U.S. Pat. Nos. 3,519,509; 3,607,565; 3,829,339; 3,445,319; 3,573,151; 3,878,591; 1,541,086; and 662,963. U.S. Pat. Nos. 3,345,232 and 2,812,797 are of interest in their showing of tube type elements for dispensing Y filaments between the hooks of continuously moving conveyor mechanisms.
It is an object of the present invention to provide novel procedure and mechanism for fabricating open weave scrim cloth formed of uniformly spaced X and Y fibers or filaments, particularly for use of such cloth in the production of urethane foam insulation. Another object is to provide a novel method and means for stringing the transverse Y filaments of such scrim cloth between mounting elements in the form of hooks on opposite longitudinally moving panels. A still further object is to provide means for introducing the X filaments adjacent to or between spaced Y weaving mechanisms, to permit such X filaments to rest on and be carried by the Y filaments.